Wikipedia
An oil bath is a type of heated bath used in a laboratory. These baths are commonly used to heat reaction mixtures. An oil bath is essentially a container of oil that is heated by a hot plate. Generally, silicone oil is used in modern oil baths, although mineral oil, cottonseed oil and even phosphoric acid have been used in the past.
Another use of an oil bath is to filter particulates out of air, by leading the air stream through an (unheated) oil bath. This type of air filter was used in car engines, but has been replaced by modern paper air filters.
Usage examples of "oil bath".
He could smell the clean hot scent of burning charcoal from the big shed up ahead of them, hot metal, sneeze-making cinders, the heavy frying smell of the oil bath used for quenching and tempering.
Edge did, however, get up early and return to his room, so Amelie's maid could be summoned to prepare her olive-oil bath.
There had been survivors' accounts of that dreadful blood-and-oil bath in the North Atlantic, some hysterical, some non-committal, but on putting them together I found that Tutte, daring, brave, resolute, was a master of the calculated risk.
She was still climbing, but gradually starting to come around onto her course, using the compass in its glass oil bath above her head, when the engine stuttered, almost cut and then surged again in full power.
Such a thorough oil bath did I give Chum that now I could not get rid of the stuff.
He was standing by the oil bath, and it hissed and bubbled smoke as he plunged the bright metal into it.
Almost at once it became anger that hissed like a red-glowing sword being tempered in an oil bath .
Moving through into the bathroom, Gromph found his sister, alone except for a pair of attendants, eyes closed and soaking in an oddly scented oil bath.
Donovan uncapped the tightly sealed container and from the oil bath within he withdrew a second cube.
So he floats in the oil bath, which turns on automatically when the ship is prepared for flight.
If you took one of your 'sisters' up there on the Moon, and gave her a chance to take off her boots, and have an oil bath and a depilation, and put on a pair of pretty sandals, and a belly jewel, and perfume, she'd love it.